WO2004100246A1

WO2004100246A1 - Method for cleaning semiconductor processing apparatus

Info

Publication number: WO2004100246A1
Application number: PCT/JP2004/005798
Authority: WO
Inventors: Tadahiro Ohmi; Masaki Hirayama
Original assignee: Tadahiro Ohmi; Masaki Hirayama
Priority date: 2003-05-08
Filing date: 2004-04-22
Publication date: 2004-11-18
Also published as: US20060281323A1; TW200504874A; JP2004335789A

Abstract

A method for cleaning a microwave plasma processing apparatus is disclosed wherein a cleaning gas is introduced and then excited with microwave plasma (step 3). By applying high-frequency power to a substrate supporting stage by which a substrate to be processed is supported (step 4), the etching rate is improved, thereby shortening the cleaning time.

Description

Description Cleaning method for substrate processing equipment

The present invention generally relates to a plasma processing apparatus, and more particularly to a microphone mouth-wave plasma processing apparatus.

The plasma processing process and the plasma processing apparatus have been used in recent years for ultra-small semiconductor devices having a gate length close to 0.1 m, which is a so-called deep submicron device or so-called deep submicron one-micron device, or less. This is an indispensable technology for manufacturing and for manufacturing high-resolution flat panel display devices including liquid crystal display devices.

Conventionally, various plasma excitation methods have been used as a plasma processing apparatus used in the manufacture of semiconductor devices and liquid crystal display devices. In particular, a parallel plate type high frequency excitation plasma processing apparatus or an inductively coupled plasma processing apparatus has been used. Is common. However, since these conventional plasma processing apparatuses have non-uniform plasma formation and a limited area of high electron density, it is difficult to perform a uniform process over the entire surface of the substrate at a high processing speed, that is, a high throughput. There is a problem that it is difficult. This problem is particularly acute when processing large diameter substrates. Moreover, in these conventional plasma processing apparatuses, there are some essential factors such as a high electron temperature, which damages a semiconductor element formed on a substrate to be processed, and causes a large metal contamination due to sputtering of a processing chamber wall. Have a problem. For this reason, it is becoming difficult for conventional plasma processing apparatuses to satisfy strict requirements for further miniaturization and further improvement in productivity of semiconductor devices and liquid crystal display devices.

On the other hand, a microwave plasma processing apparatus using a high-density plasma excited by a microphone mouth-wave electric field without using a DC magnetic field has been conventionally proposed. For example, a microwave is radiated into a processing vessel from a planar antenna (radial line slot antenna) having a large number of slots arranged to generate a uniform microphone mouth wave, and a vacuum is generated by the microphone mouth wave electric field. Plasma that excites plasma by ionizing gas in container A processing device has been proposed.

Microphone mouth-wave plasma excited by such a method can achieve high plasma density over a wide area directly below the antenna, and can perform uniform plasma processing in a short time. Moreover, in the microwave plasma formed by such a method, the plasma is excited by the microwave, so that the electron temperature is low, and damage to the substrate to be processed and metal contamination can be avoided. Furthermore, since uniform plasma can be easily excited even on a large-area substrate, it can be easily adapted to a semiconductor device manufacturing process using a large-diameter semiconductor substrate and a large-sized liquid crystal display device. Background art

FIGS. 1A and 1B show the configuration of a conventional plasma processing apparatus 100 using such a radial line slot antenna. Note that FIG. 1A is a cross-sectional view of the plasma processing apparatus 100, and FIG. 1B is a view illustrating a configuration of a radial line slot antenna.

Referring to FIG. 1 (A), a plasma processing apparatus 100 has a processing container 101 exhausted from a plurality of exhaust ports 1 16, and a substrate to be processed is contained in the processing container 101. A holding table 1 15 for holding 1 1 4 is formed. In order to realize uniform exhaust of the processing container 101, a space 101A is formed in a ring shape around the holding table 115, and the plurality of exhaust ports 116 are formed. The processing container 101 is formed at regular intervals so as to communicate with the space 101A, that is, formed symmetrically with respect to the substrate to be processed, so that the space 101A and the exhaust port 116 are formed. Can be exhausted uniformly. On the processing vessel 101, a large number of low-loss dielectrics are provided at positions corresponding to the substrate 114 on the holding table 115 as part of the outer wall of the processing vessel 101. A plate-shaped shower plate 103 having an opening portion 107 formed therein is formed via a seal ring 109, and further made of a low-loss dielectric outside the shower plate 103. A cover plate 102 is provided via another seal ring 108. The shower plate 103 is referred to as a microwave transmitting window because it transmits microwaves. The shower plate 103 has a plasma gas passage 104 formed on the upper surface thereof, and each of the plurality of openings 107 is formed so as to communicate with the plasma gas passage 104. I have. Further, a plasma gas supply passage 106 connected to a plasma gas supply port 105 provided on the outer wall of the processing vessel 101 is formed inside the shower plate 103. The plasma gas such as Ar or Kr supplied to the plasma gas supply port 105 is supplied from the supply passage 106 to the opening 107 via the passage 104, From the opening 107, it is discharged at substantially the same concentration into the space 101B immediately below the shower plate 103 inside the processing container 101.

On the processing vessel 101, further outside the cover plate 102, a radiation surface shown in FIG. 1 (B) having a radiation surface shown in FIG. A radial line slot antenna 110 is provided. The radial lines antenna 110 is connected to an external microwave source (not shown) via a coaxial waveguide 11 OA, and the microwaves from the microwave source cause the space 101 B to be closed. Excites the plasma gas released to The gap between the cover plate 102 and the radiation surface of the radial in-slot antenna 110 is filled with air. The radial line slot antenna 110 has a flat disk-shaped antenna main body 110B connected to the outer waveguide of the coaxial waveguide 111OA, and an opening of the antenna main body 110B. And a radiation plate 110C formed with a number of slots 110a shown in FIG. 1 (B) and a number of slots 110b perpendicular thereto, and the antenna body A retardation plate 110D made of a dielectric plate having a constant thickness is inserted between 110B and the radiation plate 110C.

In the radial line slot antenna 110 having such a configuration, the microwave fed from the coaxial waveguide 111OA passes between the disk-shaped antenna body 110B and the radiation plate 110C. The light propagates while expanding in the radial direction, and at this time, the wavelength is compressed by the action of the retardation plate 110D. Therefore, by forming the slots 110a and 110b concentrically and orthogonally to each other corresponding to the wavelength of the microwave traveling in the radial direction in this way, Plane wave with circular polarization The radiation plate can radiate in a direction substantially perpendicular to 110C.

By using the radial line slot antenna 110, uniform high-density plasma is formed in the space 101B immediately below the shower plate 103. The high-density plasma thus formed has a low electron temperature, so that the substrate to be processed 114 is not damaged, and metal contamination caused by sputtering of the vessel wall of the processing container 101 is prevented. It does not occur.

In the plasma processing apparatus 100 of FIG. 1, an external processing gas source (not shown) is further provided in the processing vessel 101 between the shear plate 103 and the substrate to be processed 114. A processing gas supply section 111 formed with a number of nozzles 113 for supplying a processing gas through a processing gas passage 112 formed in the processing vessel 101 from Each of the nozzles 113 discharges the supplied processing gas into a space 101C between the processing gas supply unit 111 and the substrate 114 to be processed. Between the adjacent nozzles 113 and 113 of the processing gas supply unit 111, plasma formed in the space 101B is supplied from the space 101B to the space 110B. An opening having a size that allows efficient transmission is formed by diffusion in 1C.

Therefore, when the processing gas is discharged from the processing gas supply unit 111 to the space 101C through the nozzle 113 in this way, the released processing gas is discharged to the space 101B. Excited by the formed high-density plasma, uniform plasma processing on the substrate to be processed 114 can be performed efficiently and at high speed without damaging the substrate and the element structure on the substrate. It is performed without contaminating the substrate. On the other hand, the microwave radiated from the radial line slot antenna 110 is blocked by the processing gas supply unit 111 composed of a conductor, and does not damage the substrate 114 to be processed.

The substrate processing that can be performed by the plasma processing apparatus 100 includes plasma oxidation processing, plasma nitridation processing, plasma oxynitridation processing, plasma CVD processing, and the like. By supplying an etching gas to the space 101B from the nozzle 113 and applying a high-frequency voltage from a high-frequency power supply 115A to the holding table 115, the substrate 114 is processed. Performing reactive ion etching Is also possible.

When performing a film forming process for forming a film on the substrate 114 to be processed, such as a plasma CVD process, using the plasma processing apparatus 100, the processing vessel 100 1 Deposits accumulate inside. For example, if the deposit accumulates after performing the film forming process for a long time, the deposit is separated from the portion where the deposit is deposited, which is a factor of generating particles and the like.

Therefore, cleaning for periodically removing the deposits is required. Such a plasma processing apparatus and its cleaning method are disclosed in, for example, Japanese Patent Application Laid-Open Nos. Hei 9-63 793, No. 200-507-106, and No. 200-57. It is described in No. 149 publication.

For example, when performing the cleaning, a cleaning gas is introduced from the shower plate 103 to excite the microwave plasma, thereby dissociating the cleaning gas and etching and removing the deposit. There is a way.

However, the above-described cleaning by microwave plasma cannot completely remove the deposits, or the etching rate for removing the deposits is low, so that cleaning may take time.

For example, in the lower part of the processing gas supply unit 111, that is, in the space 101C, the microphone mouth wave plasma is not excited because the microwave mouth wave does not reach, and the space 110C is not excited. Since only plasma diffused from 1 B exists, the plasma density is low and the electron temperature is low.

For this reason, there arises a problem that the deposit deposited on the portion facing the space 101C is not etched or the etching rate is low in the cleaning with the above-mentioned microwave plasma.

Specifically, a deposit on the side of the processing gas supply unit 111 facing the space 101C, and a portion of the inner wall surface of the processing vessel 101 facing the space 101C However, it was difficult to completely remove the deposits on the side walls of the holding table 115 because the etching speed of the deposits was low.

Accordingly, the present invention provides a novel and useful substrate processing apparatus which solves the above-described problems. The purpose of the present invention is to provide a programming method.

A specific object of the present invention is to provide a novel substrate processing apparatus that uses microwave plasma to efficiently perform cleaning, thereby shortening the cleaning time. Is to provide a way. Disclosure of the invention

According to the present invention, in a substrate processing apparatus using microwaves, microwave plasma is used and high-frequency power is applied to a holder for a substrate to be processed during cleaning for removing deposits deposited in a film forming process. Thus, it is possible to increase the etching rate of the deposit and shorten the cleaning time. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram schematically showing a plasma processing apparatus.

FIG. 2 is a flowchart showing a cleaning method of the substrate processing apparatus according to the present invention.

FIG. 3 is a diagram schematically showing a state in which the mouth opening plasma is excited in the plasma processing apparatus of FIG.

FIG. 4 is a diagram showing a cleaning speed according to the cleaning method of the substrate processing apparatus of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Next, embodiments of the present invention will be specifically described.

[First embodiment]

First, as an example of the substrate processing by the plasma processing apparatus 100 described above with reference to FIG. 1, a specific example in the case where a plasma CVD process is performed to form a film on the processing target substrate 114 will be described below. Show.

When the plasma processing apparatus 1 0 0 described above, in the case of forming the insulating film on the target substrate 1 1 4 in plasma C VD process, the plasma gas 0 _2, A r, the S i H ₄ process gas The silicon oxide film (S I_〇 ₂ film) by using, to form the N ₂ plasma gas in a similar manner, Ar, nitride film by using the S i H ₄ process gas (S i N film) It is possible.

Further, similarly, it is possible to form a fluorine-added carbon film (CxFy film) by using Ar and H ₂ as a plasma gas and a fluorocarbon-based gas such as C ₄ F ₈ as a processing gas.

When the above-described film forming process is performed, the silicon oxide film, the nitride film, the fluorinated carbon film, and the like are deposited in the processing container 101 as well as on the substrate 114 to be processed. accumulate.

If the deposits accumulate, they are separated from the inside of the processing container 101 and cause particles to be generated. Therefore, it is necessary to perform cleaning periodically. Therefore, the cleaning method according to the present invention is performed to clean the inside of the processing container 101 and remove the deposits as described above.

Next, a specific cleaning method of the plasma processing apparatus 100 will be described below.

FIG. 2 is a flowchart showing a cleaning method of the substrate processing apparatus according to the second embodiment of the present invention. In the case of the present embodiment, a method for cleaning the above-mentioned fluorinated carbon film will be described.

Referring to FIG. 2, first, when the cleaning step is started in step 1 (indicated as S1 in the figure, the same applies hereinafter), in step 2, a cleaning gas is introduced into the processing vessel 101. When cleaning the fluorine-added carbon film, for example, 〇 ₂ and H ₂ are used as the cleaning gas. Further, a diluting gas is further added as a diluting gas in order to dilute the cleaning gas such as 〇 ₂ and H ₂ to make the etching by the cleaning gas uniform in the processing vessel 101 and to facilitate the plasma excitation. r may be used.

So, in step 2,

Are introduced into the space 101B through the opening 107 of the shower plate 103, respectively. Next, in step 3, microwave power of 140 W from a microwave power source is introduced into the radial line slot antenna 110 to excite microwave plasma in the processing vessel 101.

Since the microwave plasma is excited in this step, the introduced 〇 ₂ / H ₂ is dissociated and reacts with oxygen radicals, hydrogen radicals, oxygen ions, hydrogen ions, etc., which contribute to the etching of the fluorine-added carbon film. Is generated, and the substantial cleaning is started by etching the fluorine-added carbon film which is a deposit in the processing container 101 as described below.

CxFy +-0 ₂ H ₂ ^ x CO † + yHF f

2 mu

Further, in this step, by adding H ₂て in addition to 0 ₂ / H ₂ as a cleaning gas, the formation of oxygen radicals, hydrogen radicals, oxygen ions, and hydrogen ions contributing to the above-mentioned etching is promoted, and furthermore, The cleaning rate can be improved.

However, if only the cleaning by the microwave plasma is used, the etching rate for removing the fluorine-containing film is low, and the cleaning may take time.

FIG. 3 schematically shows a state where the microwave plasma M is excited in the plasma processing apparatus 100. However, in the figure, the parts described above are denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 3, for example, the microwave does not reach the lower part of the processing gas supply unit 111, that is, the space 101 C, so that microwave plasma is not excited. Since only plasma diffused from 101 B exists, the plasma density is low and the electron temperature is low.

For this reason, there is a problem that the deposit deposited on the portion facing the space 101 C is not etched or the etching speed is low by the cleaning using only the microwave of the microwave.

Specifically, deposition on the side of the processing gas supply unit 111 facing the space 101C The etching speed of the material and the sediment on the inner wall surface of the processing vessel 101 facing the space 101C is slow, and the sediment on the side wall surface of the holder 115 is completely deposited. It was difficult to clean things.

Therefore, in the cleaning method of the substrate processing apparatus according to the present invention, in step 4, the high frequency power of 30 A is applied to the holding table 115 from the high frequency power supply 115 A connected to the holding table 115. Apply 0 W. The frequency of the high-frequency power supply used in this embodiment is 2 MHz, but a frequency of 500 MHz or less, preferably 100 kHz to 15 MHz is preferably used. Alternatively, a DC bias may be used.

In this step, since high-frequency power is applied to the substrate holder 115, the plasma potential oscillates, and the plasma potential in the space 101C is raised. Since the high-frequency plasma is excited in the space 101 C, the dissociation of the cleaning gas proceeds to generate reactive species such as radicals and ions necessary for etching the deposit, and the plasma potential is raised. However, the ion energy incident on the wall surface to be cleaned increases, and the etching of the deposit is accelerated. As a result, deposits on the side of the processing gas supply unit 111 facing the space 101C, a portion of the inner wall surface of the processing vessel 101 facing the space 101C, The etching rate of the deposit on the side wall surface of the holder 115 is improved, and the cleaning rate is improved.

Next, when the etching of the deposit is completed, the introduction of the high frequency power and the microwave power is stopped in Steps 5 and 6, respectively, and the cleaning is completed in Step 7.

In this embodiment, the cleaning gas and the diluting gas are introduced from the shower plate 103. However, if necessary, for example, the shower plate 103 and the processing gas supply unit 111 may be used. , Or only from the processing gas supply unit 111. It is also possible to change the ratio introduced from the shower plate 103 and from the processing gas supply unit 111.

For example, depending on the film formation conditions of the fluorine-added carbon film, it faces the space 101B. If there is much sediment in the part, increase the ratio of the flow rate of the cleaning gas and dilution gas introduced from the shower plate 103, and if there is much sediment in the part facing the space 101C. By increasing the ratio of the flow rates of the cleaning gas and the dilution gas introduced from the processing gas supply unit 111, the cleaning gas can be used efficiently. As a result, it is possible to perform more efficient cleaning while suppressing the amount of the cleaning gas used and improving the cleaning speed.

In order to confirm that the removal of the deposits in the processing container 101 has been completed and the cleaning has been completed, there is a method of monitoring the emission state of plasma. For example, the light emission during cleaning is spectrally processed by a spectroscope or the like, so that the change in the intensity of light of a specific wavelength is monitored, and when the change in emission intensity converges, the cleaning is terminated, and cleaning is performed. Has been detected.

Further, depending on the deposition state of the deposit to be cleaned, for example, when there is a large amount of deposit in a portion facing the space 101C, the time for applying the high-frequency power is increased to efficiently perform the cleaning. The rate can be improved. In addition, the time to introduce microwave power and the time to introduce high-frequency power as necessary, and the timing to introduce and stop microphone mouth wave power and the time to introduce and stop high-frequency power were changed, It is possible to perform efficient cleaning according to the amount of the cleaning. If necessary, cleaning can be performed using only high-frequency plasma with high-frequency power.

In the above-described embodiments, the method of cleaning the fluorine-added carbon film was described. For example, a silicon oxide film (Si ₂ film), a fluorine-added silicon oxide film (S i OF film), and a silicon nitride film (S An insulating film such as an iN film can be cleaned in the same manner.

Wherein the S I_〇 ₂ film, S i OF film, etc. S i N film, the gas of the fluorine compound in the cleaning gas, for example _{_{_{NF 3, CF 4, C 2}}} F 6, SF 6 by using the like, FIG. 2 The cleaning can be performed by the method described in (1), and the same effect as in the case of cleaning the above-mentioned fluorine-added film can be obtained.

Further, for example, fluorine-doped force one carbon film and S I_〇 ₂ film, S i OF film, S i N film is laminated NF ₃ and NF ₃ are used for cleaning the deposited deposits and for cleaning deposits in which an inorganic insulating film and an organic insulating film are mixed, such as a S i CO film and a S i CO (H) film. _2, H _2, H ₂ using a 0 mixed with gas as the cleaning gas, or cleaning and 〇 ₂ according to NF _3, H _2, H ₂ 〇 a by cleaning the like performed alternately possible to perform cleaning by It is. Also in this case, the same effect as in the case of cleaning the fluorine-containing carbon film can be obtained.

[Second embodiment]

Next, FIG. 4 shows the cleaning speed (rate) when cleaning is performed using the method for cleaning the substrate processing apparatus shown in FIG. 2 in the first embodiment. However, in the description, the same reference numerals have been used in the above description, and description thereof will be omitted.

FIG. 4 shows the cleaning speed when the fluorinated carbon film was cleaned by the method described in the first embodiment, and the high-frequency power to the holding table 115 was changed to 300. The results for W (B) and 500 W (C) are shown. Further, for comparison, the results of the case (A) in which cleaning was performed only with microwave plasma without applying high-frequency power to the holding table 115 are also shown. Referring to FIG. 4, when cleaning was performed using only microwave plasma (A), the cleaning speed was 194 nm / min, while when 300 W of high-frequency power was applied (B), The cleaning speed is 540 nm / min, and the cleaning speed is 2.8 times that of the case (A) where no high-frequency power is applied. Further, when the high-frequency power is set to 500 W (C), the cleaning speed is 680 nm / min, and the cleaning speed is 3.5 times higher than when no high-frequency power is applied (A). It is possible to reduce the time.

As described above, by applying high-frequency power to the holding table 115, deposits on the side of the processing gas supply unit 111 facing the space 101C, The effect of increasing the cleaning rate by increasing the etching rate of the deposit on the inner wall surface of the processing vessel 101 facing the space 101C and the side wall surface of the holding table 115 can be obtained. It is thought that it is because.

Also, in order to protect the surface of the holding table 115, on the holding table 115, for example, A 1 ₂ 0 ₃ Ya 3 i N by placing the protective wafer made of a sintered ceramic such as may be implemented chestnut-learning.

In addition, the above-described cleaning can be performed every time one film formation process of the substrate to be processed is completed. For example, the cleaning is performed each time the film formation process of a plurality of substrates to be processed is completed. It is also possible.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the above-described specific embodiments, and various modifications and changes are possible within the scope of the claims. . Industrial applicability

Advantageous Effects of Invention According to the present invention, in a substrate processing apparatus using microwave plasma that can easily excite uniform plasma even on a large-area substrate, cleaning time can be reduced by performing cleaning efficiently. It becomes. Therefore, it is suitable for use in a manufacturing process of a semiconductor device using a large-diameter semiconductor substrate or a manufacturing process of a large-sized liquid crystal display device.

Claims

The scope of the claims

1. A processing vessel defined by an outer wall;

A holding table provided in the processing container and connected to a high-frequency power supply, for holding a substrate to be processed;

An exhaust port for exhausting the inside of the processing container,

On the processing container, a microwave transmission window provided as a part of the outer wall so as to face the substrate to be processed,

A microphone mouth wave antenna provided on the microphone mouth wave transmission window and electrically connected to a microphone mouth wave power supply;

A plasma gas supply unit for supplying a plasma gas into the processing container,

A cleaning method for a substrate processing apparatus, comprising a processing gas supply unit provided between the substrate to be processed on the holding table and the microwave transmission window so as to face the substrate to be processed. hand,

A gas introduction step of introducing a cleaning gas into the processing container,

A plasma excitation step of introducing a microphone mouth wave into the processing container from the microwave antenna to excite plasma in the processing container,

A cleaning method for a substrate processing apparatus, further comprising a bias marking step of applying high-frequency power from the high-frequency power supply to the holding table.

2. The method for cleaning a substrate processing apparatus according to claim 1, wherein the processing gas supply unit is made of a conductive material and grounded.

3. The microwave antenna is fed by a coaxial waveguide, and has an antenna body having an opening, and a microphone mouth wave radiation surface having a plurality of slots provided on the antenna body so as to cover the opening. 3. The cleaning method for a substrate processing apparatus according to claim 1, wherein the cleaning method comprises a dielectric provided between the antenna main body and the microphone mouth wave radiation surface.

4. The cleaning method for a substrate processing apparatus according to any one of claims 1 to 3, wherein the cleaning gas contains oxygen.

5. The cleaning method for a substrate processing apparatus according to any one of claims 1 to 4, wherein the cleaning gas contains hydrogen.

6. The cleaning method for a substrate processing apparatus according to any one of claims 1 to 5, wherein the cleaning gas contains H ₂ 〇.

7. The cleaning method for a substrate processing apparatus according to any one of claims 1 to 6, wherein the cleaning gas contains a fluorine compound.

8. The claim according to claim 1, wherein the cleaning gas is introduced from the plasma gas supply unit formed between the microwave antenna and the processing gas supply unit. The cleaning method of the substrate processing apparatus according to any one of the above.

9. The cleaning method for a substrate processing apparatus according to any one of claims 1 to 8, wherein the cleaning gas is introduced from the processing gas supply unit.

10. The cleaning gas is dissociated by the microwave plasma and the high-frequency plasma excited by the high-frequency power to become a reactive species, and etches a deposit deposited inside the processing chamber by the reactive species. The method for cleaning a substrate processing apparatus according to any one of claims 1 to 9, wherein the cleaning is performed.

11. The cleaning method for a substrate processing apparatus according to claim 10, wherein the deposit includes a fluorine-added carbon film.